If you've been into survival camping for any length of time, you are no doubt familiar with the 10 C's of Survivability made popular by The Pathfinder School. Before serving as an instructor at that school, I had always carried some version of the 10 C's, at times with oddball items that would never get used or were simply not necessary.
Over the years, we kept dialing this list down to the 10 essentials- basically 1 of each item, then we started removing items until we got down to 1 item or nothing at all at which time we had to recreate an item. Here's sorta how that played out:
All in a Haversack
Basic/Intermediate
Cutting Tools: Knife & Folding Saw
Combustion Device: Ferro Rod, Lighter, & Flint and Steel
Cover: Emergency Tarp & 2 Drum Liners
Container: 32+ oz Steel Bottle with Nesting Cup
Cordage: 100 feet #36 Tarred Bankline
Cargo: Gorilla Tape
Compass: Orienteering Type with Pace Beads
Candling Device: Head Lamp + Spare Batteries
Combination Tool: Multi-tool or Swiss Army Knife
Cloth: 3'x3' 100% cotton shemagh
Advanced
Cutting Tools: Knife
Combustion Device: Flint & Steel
Cover: Emergency Tarp & 2 Drum Liners
Container: 32+ oz Steel Bottle with Nesting Cup
Cordage: 100 feet #36 Tarred Bankline
More Advanced
Knife Only
Recreate:
Water vessel (Burned Bowl or Clay)
Cordage (Natural Material)
Cover (Debris Shelter)
Combustion (Bow Drill)
So, you can see that IF we got or used a haversack, it was primarily used to collect materials for projects the more advanced you got in skills. The Longhunters of old used their haversacks in a similar fashion. Very few, if any are documented as loading them up as we do today in the survival/bushcraft world.
Then, of course, you have those that go the opposite way by packing hammocks, ponchos, stoves, and all into haversacks, making them look more like backpacks. I don't agree with this method at all UNLESS it's on a pack frame such as a Roycraft. Even then, I personally, am not a fan
The following is an excerpt from my book The Gospel of Survival on what we recommend to carry for the beginner in the haversack.
Equipped to Survive
The Complete 12 C's Survival Kit (Emergent C's)
The 12 C's represent categories of items that are essential to survival. The first 5 items we discussed are considered E.D.C. items with the following 7 to be considered items that make survival more convenient. This kit would be a Tier 2 kit or one that is attached to your body by way of a bag such as a haversack or small backpack. As more items are added to each category a Tier 3 kit, which would be carried by conveyance such as a cart, horse or vehicle would be realized. Tier 3 or 4would be more conducive for longer-term wilderness activities, building, and living.
Cutting Tools: Knife, Ax, Saw
Combustion Device: Bic lighter, Fire Steel & Quick Fire
Cover: Tarp, Tent, Hammock, etc.
Container: 32+ oz Steel with Nesting Cup & Bushpot
Cordage: 100+ feet of Paracord & #36 Tarred Bankline
Cargo: Cargo Tape such as Gorilla Tape
Compass: Orienteering Type with Pace Beads
Candling Device: Head Lamp + Spare Batteries
Combination Tool: Multi-tool or Swiss Army Knife
Cloth: 3'x3' 100% cotton shemagh or 3XL Orange T-shirt
Cerate: Medicinal Salves, Medications, etc.
Circumvention: Water Filters, Cuff Keys, Lock Picks, and other work-around tools
Over the years, I've opted to carry less and less when I go into the woods. When I go by myself for a day, I carry a neck knife most often, and here's what I carry in my haversack:
Ferro Rod or Lighter (rarely both)
50ft Cordage
Grayl Water Filter
Silky Pocket Boy
a snack (or 3)
So, what size haversack is right for you?
Well, it depends on what you plan to carry. If you're going to pack light and you are of average size (220lb or less), then the Traditional Haversack would suit you just fine. You can carry a small water vessel and your other 4 C's without issue with a little room to spare. If you plan to carry your complete 12 C's kit, you'll definitely need the XL Haversack. You can carry your 12 C's and add in a poncho or small bedroll with the Woodcraft Haversack.
Hope you found this helpful!